A hinge assembly of this type typically includes a fixed member, a movable member connected to the fixed member such that the movable member is rotatable and movable toward and away from the fixed member and a coiled spring biasing the movable member toward the fixed member. A pair of spherical bodies are provided on an opposing surface of the movable member facing the fixed member and a pair of cam surfaces are provided on an opposing surface of the fixed member facing the movable member. The pair of spherical bodies and the pair of cam surfaces respectively abut against one another when the movable member is in a predetermined rotational angle range with respect to the fixed member. The spherical bodies and the cam surfaces in respective abutment with one another convert a biasing force of the coiled spring into a rotational biasing force. The rotational biasing force causes the movable member to be rotated to a predetermined rotation position with respect to the fixed member and to be maintained at the rotation position.
The fixed member is adapted to be rotatable through a predetermined slight angle with respect to other members of the hinge assembly or tubular portions, etc., of a pair of housings rotatably connected by the hinge assembly, and when the movable member is in the predetermined rotational angle range, the fixed member is rotated through the predetermined slight angle by the rotational biasing force converted by the spherical bodies and the cam surfaces. As a result, hitting portions formed in the fixed member and in the other members or the tubular portions abut against each other at a high speed. This generates a clicking sound.
Patent Document 1 Japanese Unexamined Patent Application Publication No. 2001-152728.
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2002-181031.